Fuels based on biocomponent sources will likely become increasingly prevalent in the future. Already, various governments have instituted current and future requirements that motor fuel pools contain a minimum percentage of fuel derived from a biocomponent source, such as a plant, animal, fish, or algae based oil or fat.
For production of diesel fuel, vegetable oils such as canola oil, palm oil, or other similar oils have been identified as potentially suitable based on the carbon chain length of the vegetable oil. However, biocomponent feedstocks are known to often have high hydrogen consumption during hydroprocessing. Providing hydrogen from a separate, outside source in a refinery will often raise costs to a point that is not economical. Thus, when a new process is added in a refinery that requires hydrogen, the addition often requires a reduction in volume in another process. Since biocomponent feeds can have relatively high hydrogen consumption per volume as compared to mineral feeds, multiple barrels of mineral diesel production may have to be removed from service for each added barrel of biocomponent feed. Thus, methods of reducing the needed hydrogen for processing biocomponent feed are desirable.
U.S. Published Patent Application No. 2008/0154073 describes a process for removing oxygen from biocomponent molecules at low hydrogen pressure. The feed is exposed to a supported hydrogenation catalyst, such as Ni, NiMo, Pt, or Pd in the presence of 150-290 psi (1034-1999 kPa) of hydrogen. It appears that the ratio of hydrogen treat gas to feedstock is not disclosed.
U.S. Published Patent Application No. 2008/0161614 describes two-stage co-processing of a feed including both vegetable/animal and mineral oil. The first stage is operated at lower severity to primarily treat the vegetable and/or animal oil in the feed. The product of the first stage is then stripped to remove gas phase impurities. The stripped product is then hydrotreated in a more severe hydrotreatment stage to produce a diesel fuel.
U.S. Published Patent Application No. 2008/0173570 describes a method for hydroprocessing involving two catalyst beds, where a biocomponent feed is introduced in the second bed. It is disclosed that reducing the temperature and the pressure leads to lower hydrogen consumption during removal of oxygen from the biocomponent feed. All of the examples appear to involve a treat gas ratio of 320 Nl/l (1900 scf/bbl).
International Publication No. WO/2008/040980 describes reducing hydrogen consumption by controlling the products from reactions to remove oxygen from biocomponent feeds. Lower hydrogen pressures are mentioned as helping to reduce hydrogen consumption, but such pressures are mentioned as also leading to catalyst deactivation. The examples appear to involve a treat gas ratio of 200 Nl/l (1185 scf/bbl).
European Publication No. EP 1719811 describes a method for producing liquid hydrocarbons from biomass. The method includes forming an aqueous slurry of the biomass and particles of a layered catalyst, such as a clay. The slurry is heated to a temperature between 250 and 400° C. Up to 10 bars (1000 kPa) of hydrogen may optionally be added, although the publication states that it is preferred to perform the process without added hydrogen.
European Publication No. EP 1741767 describes a process for producing diesel fuel from biocomponent sources. EP 1741767 states that the process reduces the needed hydrogen consumption by adding a sulfur-containing compound to the biocomponent feed.